1. Field of the Invention
The present invention generally relates to spinal implants. More particularly, certain embodiments of this invention relate to ceramic implants having supportive bodies and bone growth promoting inserts.
2. Description of Related Art
An intervertebral disc may degenerate. Degeneration may be caused by trauma, disease, and/or aging. An intervertebral disc that becomes degenerated may have to be partially or fully removed from a spinal column. Partial or full removal of an intervertebral disc may destabilize the spinal column. Destabilization of a spinal column may result in alteration of a natural separation distance between adjacent vertebrae. Maintaining the natural separation distance between vertebrae may prevent pressure from being applied to nerves that pass between vertebral bodies. Excessive pressure applied to the nerves may cause pain and/or nerve damage. During a spinal fixation procedure, a spinal implant may be inserted within a space created by the removal or partial removal of an intervertebral disc between adjacent vertebrae. The spinal implant may maintain the height of the spine and restore stability to the spine. Bone growth through or around the spinal implant may fuse the adjacent vertebrae.
A spinal implant may be inserted during a spinal fixation procedure using an anterior approach, lateral approach, posterior approach or combination approach. In some situations, an anterior approach may result in an easier approach, less muscle and tissue damage, and less bone removal than other approaches. During some spinal implant insertion procedures, a plate, or bone fastener may be used to augment fusion and/or to inhibit expulsion of the spinal implant.
A discectomy may be performed to remove or partially remove a defective or damaged intervertebral disc. The discectomy creates a disc space for a spinal implant. The amount of removed disc material may correspond to the size and type of spinal implant to be inserted. After a discectomy, a spinal implant may be inserted into the disc space. One or more spinal implants may be inserted between a pair of vertebrae. Spinal implants may be inserted into disc spaces prepared between more than one pair of vertebrae during a spinal fusion procedure.
Spinal surgery may be complex due in part to the proximity of delicate soft tissue such as the spinal cord, cauda equina, and/or vascular structures. Preparation instruments and spinal implants may need to be carefully inserted to avoid damage to soft tissue. Alignment and spacing of a spinal implant that is to be inserted into a patient may be determined before surgery. Achieving the predetermined alignment and spacing during surgery may be important to achieve optimal fusion of adjacent vertebrae.
Bone growth promoting material may be used in conjunction with an implant to facilitate bone growth that will fuse vertebrae together. Bone growth promoting material may include bone. Bone may be autogenic bone, allogenic bone, xenogenic bone or combinations thereof. Autogenic bone is bone obtained from another location of a patient. Allogenic bone is bone derived from the same species as the patient. Xenogenic bone is bone derived from a species other than that of the patient. Bone growth promoting material may include, but is not limited to, bone marrow, calcium phosphates, collagen, calcium sulfates, demineralized bone matrix, bone morphogenetic proteins, and/or platelet derived growth factors. The calcium phosphates may be hydroxapatite, alpha tricalcium phosphate, or beta tricalcium phosphate. Implants may be formed of metal, polymers, ceramics, autogenic bone, allogenic bone, xenogenic bone, or combinations thereof.